Side-ring EXTRA · Joint address
Pattern of Toras Kohanim / classical treatment of openings addressed to Moshe and Aharon together (as at the start of the zav section, 15:1, and elsewhere in nega law).
English: “Hashem spoke to Moshe and to Aharon” — to teach that in the law of house afflictions as well, the kohen is partnered in the speech, for purity and impurity depend on his word.
Kohen’s role in house nega
House-nega law, like person-nega, is framed as a joint communication so that Aharon’s line — the kohanim who inspect — is present from the first word of the section.